The design, conduct and analysis of the studies to be conducted under the auspices of the Projects of this Program will benefit from expertise in biostatistics and epidemiology. The primary mission of the Biostatistics/Epidemiology Core (Core D) will be to assure the validity of study findings by providing comprehensive statistical, epidemiologic, and data management support. The specific aims of this Core are: 1) to establish methods that promote adherence to standard protocols with particular attention to data collection and management; and 2) to collaborate with Project investigators in designing studies and analyzing data. Serving for the past 11 years as the WIHS Data Management and Analysis Center (WDMAC), Core D investigators have extensive experience with study design and analysis, collaborative research, and the study of HIV infection in women. Specifically, we have been at the forefront of leading and supporting HIV epidemiologic research studies. In addition, we have experience both with other program projects, and other studies of HIV pathogenesis. Our collective experience provides a strong framework to support the multifaceted data demands of this program project. Core D will provide data management and analytical support to each of the four Projects. In collaboration with Clinical Core investigators, we will provide epidemiologic and statistical expertise in identifying the characteristics and numbers of individuals for evaluation. The Core will work closely with the Tissue Culture and Virology Laboratory Core in establishing protocols for optimal data management and quality assurance. The Core will assist the Administrative Core in its oversight function by reporting on quality assurance and progress in statistical analysis. We will work with the Clinical and Administrative Cores on data collection, storage and transfer, providing optimum security of data and ease of use by investigators. These collaborations are aided by the history of collegial, productive working relationships between Core D leaders and Project/Core leaders. Dr. Elizabeth Golub will act as the Core Director and Dr. Stephen Gange as the Co-Director. The activities of the Core will occur in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Heath. RELEVANCE (See instructions): The Biostatistics/Epidemiology Core will provide guidance and expertise that will enable the appropriate analysis of data collected by the four projects. By this contribution to the interpretation of the data, Core D will engage in the broader understanding of HIV pathogenesis and support the ability of these projects to make important contributions to science.